It is well-known that the overexpression of estrogen receptor α(ERα) may lead to ER-positive breast cancer, which accounts for 70% of breast cancer.63,64 Approved endocrine therapies include aromatase inhibitors(AIs) such as Letrozole, selective ER modulators (SERMs) such as Tamoxifen, and selective ER degrader (SERDs) such as Fulvestrant. The gene discussed is CYP19A1; the disease is breast carcinoma.